I think character development is the best hook. If a reader is interested in what the protagonist is doing, going through, feeling or experiencing, you have them for the concept of the story (most of the time ).

This can be achieved very simply. EG:
She looked up as the shadow cast a contorted shape across the floor.

The reader is instantly invested in what is happening. Simple. Nothing really "high concept" about this sentence. Just a simple statement of a particular event happening to a woman/girl.

PS: Take this post with a grain of salt. I am not really sure of what you mean by the term "high concept".